A COMPARISON BETWEEN MCPA AND PESCO is-I5 FOR THE ...

The germination percentages for the treatments
were transformed by the angular
transformation (LeClerg et al. 1962) and
subjected to an analysis of variance. At the
time of assessment the post-emergence
treatments had not been applied. For
purposes of this comparison, therefore, all
treatments other than pre-emergence application
should be considered as untreated.
The results of this analysis indicated
highly significant effects due to treatments.
The untreated plots gave a uniform germinanation
of about 90 per cent each, while the
pre-emergence treated plots gave well below
40 per cent germination. Within the preemergence
treatment plots, there was no
significant difference in effect due to MCPA
and Pesco 18-15 at the same dosage levels,
i.e. at 5pts/acre or 3ptsjacre. There were,
however, significant differences in effects due
to the different dosage levels of application.
At the higher dosage rate of 5ptsjacre of
either MCPA or Pesco 18-15, there was a
more significant depression in total germination.
The drastic effect of the herbicide on
germination is evidently due to the fact that
the broadcast seeds were exposed to direct
contact with the herbicide at the time of
application.
The effect of pre~emergence application is
further indicated by the total percentage
germination for treated and untreated plots
(Table 1 above). There was a considerable
drop in the plots with the pre-emergence
treated plots.
TABLE 2
Tillering.-Tillering was observed in all plots
21 days after sowing, but the degree of
tillering differed with the treated and untreated
plots. The figures in Table 2 below
sho~ the mean number of tillers per plant
per plot. These were based on counts from
10 plants taken at random in each plot.
These counts were transformed by the
square root transformation, using the
formula YV+0.5 (LeClerg et al. 1962), and
then subjected to an analysis of variance.
This showed that differences due to treatment
were just significant at the 5 per cent level.
Further examination using Duncan's (1955)
shortest significant range test revealed that the
pre-emergence treatments significantly affected
the degree of tillering in the crop. As the
post-emergence application had not been
applied at the time of assessment it was not
strange that post-emergence treatments did
not show any significant differences from the
"weeded" and "unweeded plots".
Flowering.-Flowering was delayed by preemergence
application but post·emergence
application 4 weeks after planting had no
effect on the flowering period. The delay in
flowering was about a week, being 108 days
for the pre-emergence plots as against 101days
for the post.,emergence, hand weeded and
unweeded plots. .
Crop Health.-The effect of the herbicide
application on the general growth of the
crop was assessed by guided visual scoring.
The scale used is based on the one used by
Green & Kalogeris (1963) and is given
below as Table 3.
EFFECf OF TREATMENT ON NUMBER OF TILLERS PER PLANT
(a) Standard Error of the Mean- ± 0.28
(b) Shortest SignificantRange (Rp)
p.: (2) (3) (4) (5) (6) (7) (8) (9) (10)
2.97 3.12 3.21 3.27 3.32 3.35 3.37 3.39 3.4
Rp 0.83 0.87 0.90 0.92 0.93 0.94 0.94 0.95 0.9
(c) Ranked Mean of Treatments
Post-em Post-em Post-em Clean No Post-em Pre-em Pre-em Pre-em Pre-em
Treatment
Orig.
MCPA
3ptjac
3.7
Pesco
5ptjac
3.7
pesco
3ptjac
4.7
Weeding
4.7
Weeding
5.0
MCPA Pesco Pesco
5ptjac 5ptjac 3ptjac
5.3 8.3 8.3
Pesco MCPA
3ptjac 5ptjac
8.3 11.0
Transf. 2.0 2.0 2.2 2.2 2.3 2.4 2.8 2.9 2.9 3.4